System Backup

From Wikipedia, the free encyclopaedia
“In information technology, a backup or the process of backing up refers to making copies of data so that these additional copies may be used to restore the original after a data loss event. Backups are useful primarily for two purposes. The first is to restore a state following a disaster (called disaster recovery). The second is to restore small numbers of files after they have been accidentally deleted or corrupted. In the modern era of computing there are many different types of data storage devices that are useful for making backups. There are also many different ways in which these devices can be arranged to provide geographic redundancy, data security, and portability. Before data is sent to its storage location, it is selected, extracted, and manipulated. Many different techniques have been developed to optimize the backup procedure. These include optimizations for dealing with open files and live data sources as well as compression, encryption, and de-duplication, among others.

It is also important to recognize the limitations and human factors involved in any backup scheme.”

STORAGE MEDIA

Regardless of the repository model that is used, the data has to be
stored on some data storage medium somewhere.

Magnetic tape

Magnetic tape has long been the most commonly used medium for bulk data storage, backup, archiving, and interchange. Tape has typically had an order of magnitude better capacity/price ratio when compared to hard disk, but recently the ratios for tape and hard disk have become a lot closer. There are a myriad of formats, many of which are proprietary or specific to certain markets like mainframes or a particular brand of personal computer.

Tape is a sequential access medium, so even though access times may be poor, the rate of continuously writing or reading data can actually be very fast. Some new tape drives are even faster than modern hard disks. A principal advantage of tape is that it has been used for this purpose for decades (much longer than any alternative) and its characteristics are well understood.

Hard disk

The capacity/price ratio of hard disk has been rapidly improving for many years. This is making it more competitive with magnetic tape as a bulk storage medium. The main advantages of hard disk storage are low access times, availability, capacity and ease of use. External disks can be connected via local interfaces like SCSI, USB, FireWire, or eSATA, or via longer distance technologies like Ethernet, iSCSI, or Fibre Channel. Some disk-based backup systems, such as Virtual Tape Libraries, support data de-duplication which can dramatically reduce the amount of disk storage capacity consumed by daily and weekly backup data.

The main disadvantages of hard disk backups are that they are easily damaged, especially while being transported (e.g., for off-site backups), and that their stability over periods of years is a relative unknown.

Optical storage

Blu-ray Discs dramatically increase the amount of data possible on a single optical storage disk. Systems containing Blu-ray discs can store massive amounts of data and be more cost efficient than hard drives and magnetic tape. Some optical storage systems allow for catalogued data backups without human contact with the discs, allowing for longer data integrity.

A recordable CD can be used as a backup device. One advantage of CDs is that they can be restored on any machine with a CD-ROM drive. (In practice, writable CD-ROMs are not always universally readable.) In addition, recordable CD’s are relatively cheap. Another common format is recordable DVD. Many optical disk formats are WORM type, which makes them useful for archival purposes since the data can’t be changed. Other rewritable formats can also be utilized such as CD-RW or DVD-RAM.

Floppy disk

During the 1980s and early 1990s, many personal/home computer users associated backup mostly with copying floppy disks. The low data capacity of a floppy disk makes it an unpopular and obsolete choice today.

Remote backup service

As broadband internet access becomes more widespread, remote backup services are gaining in popularity. Backing up via the internet to a remote location can protect against some worst-case scenarios such as fires, floods, or earthquakes which would destroy any backups in the immediate vicinity along with everything else. There are, however, a number of drawbacks to remote backup services. First, internet connections (particularly domestic broadband connections) are generally substantially slower than the speed of local data storage devices, which can be a problem for people who generate or modify large amounts of data. Secondly, users need to trust a third party service provider with both privacy and integrity of backed up data. The risk associated with putting control of personal or sensitive data in the hands of a third party can be managed by encrypting sensitive data so that its contents cannot be viewed without access to the secret key. Ultimately the backup service must itself be using one of the above methods, so this could be seen as a more complex way of doing traditional backups.

Recommended backup minimums

Your decision to use tapes, hard drives or some other media will be dependant on the specific requirements of your system’s setup. For example, the latest MS operating systems have native support for backup to hard drives only. However, 3rd party software is available to provide access to magnetic tape.

Either way, our minimum recommendations for backup are as follows:

Have at least 2 weeks of backup available for access when required. Monthly, quarterly or annual backups can be included in the standard backup rotation with the media and put aside for safe keeping.

Keep all backup media off-site in a secure location (refer to our document on “Disaster Preparations”). Only have on-site the media for last night and tonight’s backup.

Ensure that staff responsible for backup fully understand the importance of the task.

Have Chaptech monitor your backup through Kaseya (refer to our document on “Kaseya IT Services”).

The costs below are a comparison between the 2 systems that Chaptech considered to be appropriate for most small to medium businesses. The per gigabyte cost has been based on backing up 300GB daily with a retention of data on a 2 week cycle.

Note: Our recommendations and comparisons don’t include remote backup services as a serious contender because current Internet speeds prohibit the transferring of large amounts of data on a daily basis. Our recommendations will be reassessed as Internet speeds approach LAN speeds.